Instagram, which Facebook acquired for about $1 billion in April, is now 12x bigger since the acquisition. Despite Facebook's stock troubles, the company is still valued at around $42 billion. In 2011, we valued Instagram at $100 million.

Pinterest, which actually has better user engagement than Facebook, recently raised a $100 million round at a $1.5 billion valuation. But we estimate, taking into consideration Pinterest's revenue, is valued at $2 billion.

Software management program and collaboration tool GitHub was another miss. With assumed revenues of $50 million a year, we estimate the company is valued at around $500 million.

Path, the mobile-only social network for close friends and family, doesn't have a significant number of daily active users nor any revenue, but it's a company that many, including Mark Zuckerberg, are watching very closely. It recently raised a $30 million round valued at $250 million, but we estimate it's worth around $180 million, which is still significant for a company without any revenue.